Subcontractor Retention Tracking Automation for Construction Teams

What retention is and why spreadsheets struggle with it

Retention is an agreed share of each payment that the paying party holds back until the work is complete, as security that the subcontractor will finish and fix defects. In the UK a common arrangement holds back about 5 percent, releases half of it at completion, and releases the rest after a defects period that is often around 12 months. Other markets set their own rates, so the rate must be read from each subcontract rather than assumed.

A spreadsheet can hold these numbers well at the start of a job. The trouble comes later. Each package can carry a different rate, a different release condition and a different date. Variations change the measured value, and a change to one line can alter the retention on several rows. One wrong formula or one copied total can carry through every later month before anyone notices. Practitioners who manage this well recommend letting software calculate retention automatically and reconciling the held balance against the paying party's records every month. Automation does the arithmetic and the cross-checking. The judgement about whether a package is ready for release stays with people.

Who this is for

The service suits any business that pays subcontractors and holds back retention on the work. That includes main contractors, developers who pay trade packages directly, specialist trades that carry retention from their own clients, and facilities firms that run project-based work. The size of the business matters less than the number of open packages and the number of people who touch each payment. A firm with five live packages and one site manager has the same logic as a group with several hundred packages across regions. The difference is how many approvals sit in the queue each month.

The person who typically runs this work is a quantity surveyor, a project accountant or an office manager who reconciles site measurements with the accounts. If that person spends the last week of each month rebuilding the retention schedule by hand, the work is a good candidate for automation.

What is included

• A register of every subcontract package, with its retention rate, release conditions, key dates and contract references.
• Logging of each payment application as it arrives, whether as a PDF, an emailed form or a file export, with the period, the claimed values and the reference recorded in one place.
• Matching of each claimed value against the measured work and the approved variations, with every difference listed for a person to review.
• Retention calculated per package and as a running balance for each project.
• A release diary that shows the dates for partial releases, defects-period releases and any milestone release, with reminders sent to the approver before each date.
• A compliance document check before approval. The worker lists which documents each package requires under its contract, such as insurance certificates, lien waivers where the contract calls for them and close-out papers, and marks any that are missing or out of date.
• An approval queue in which the site manager or quantity surveyor approves or rejects each amount, and the decision and name are recorded.
• A monthly reconciliation showing retention held, released and outstanding, ready to compare with the paying party's own statement.
• Outputs in the spreadsheet or accounting system the business already uses, so the team does not need to learn a new platform to read the results.

How it runs

1. Audit. The engagement starts with a free automation audit. The audit reviews a sample of subcontracts, the current spreadsheet, the approval chain and the documents each package needs. It measures how many applications arrive each month and how long the current cycle takes.
2. Process map. The team maps the current steps from application to payment and from completion to release. The map shows where the retention data is typed, copied or checked, and where the approvals sit. The owner signs off the map before any build starts.
3. Build. The AI worker is configured to the agreed map. It is set up with the contract terms for each package, the document checklist and the approval rules. Test applications from past months are run through it and the results are compared with the figures already paid.
4. Run. For a set period the worker runs alongside the existing spreadsheet. Differences are reviewed each month. Once the approver is satisfied with the matching, the worker becomes the main record.
5. Support. Support covers changes to contract terms, new packages, new document types and questions about a flagged item. The owner keeps the right to change the rules at any time.

What the client provides

• Copies of the subcontracts or the key terms from each: retention rate, release conditions, defects period and document requirements.
• Access to the current retention spreadsheet and a few months of past payment applications for testing.
• The measured work records and the variation approvals, in whatever form they are kept.
• A named approver for each project, usually the site manager or quantity surveyor, and a named owner who signs off the process map.
• The paying party's retention statements, so the reconciliation can be compared with their figures.

Typical timeline

The table below shows the planning lengths AiStaffo uses for this kind of engagement. These are planning assumptions. The audit confirms the exact plan for each business, because the number of packages, the number of projects and the formats of the incoming documents change the length of each phase.

What the system does not do

The worker does not approve payments, and it does not decide whether work is defective, complete or accepted. Those judgements belong to the site manager or quantity surveyor. It also does not interpret a disputed contract clause. Where a subcontract is unclear, a person or a construction lawyer must settle the reading before the worker is configured.

Matching depends on the quality of the measured work. If site measurements are late, incomplete or recorded in a different unit from the contract, the worker will flag more differences, not fewer. Scanned or handwritten documents may need a person to check the extracted figures. The worker cannot see a payment that was made outside the logged process, so cash payments and informal side arrangements need to be recorded in the same register.

The rules themselves are also moving. A UK bill reported as introduced in May 2026 would prohibit cash retention in construction contracts. At the time of the source, it had not received Royal Assent and retention remained lawful and in normal use. A business that holds retention should check the status of the bill before changing its contract template. Automation does not remove the need to know which rules apply to each contract.

The UK notice rules that matter for retention

In England and Wales, the Housing Grants, Construction and Regeneration Act 1996 sets the payment notice regime for most construction contracts. Under section 111, the paying party must pay the notified sum by the final date for payment unless it serves a valid pay-less notice before that date. The notice must state the sum it considers due and how that sum is calculated. A late or vague notice can make the full amount payable. Under section 112, a payee that is not paid the notified sum may suspend work after giving at least seven days' written notice. The worker tracks these dates in the diary so that a person can act on them. It does not decide whether a notice is valid.

This explains the rule in general terms; it is not legal or tax advice for your case.